During Saturday’s controversial match, Williams was given a code violation for coaching, which she argued. That led to two more violations, which cost her a point and then a game. Naomi Osaka defeated Williams and became the first Grand Slam tournament champion from Japan.

King praised Osaka, noting that she “played excellent tennis” and “was the best player on the court on Saturday.”

“But that’s not what many will remember,” she wrote. Instead, the game was overshadowed ― largely because of the actions of chair umpire Carlos Ramos.

“Ramos crossed the line. He made himself part of the match,” King wrote in a passionate op-ed for The Washington Post, published Sunday. “He involved himself in the end result. An umpire’s job is to keep control of the match, and he let it get out of control.”

She went on to argue that Williams ― despite her many wins ― is still treated differently than male athletes are.

“Did Ramos treat Williams differently than male players have been treated?” King wrote. “I think he did. Women are treated differently in most arenas of life. This is especially true for women of color. And what played out on the court yesterday happens far too often.”

King, who founded the Women’s Tennis Association, has not shied away from speaking out against sexism.

She has also come to Williams’ defense before, slamming French Open officials for “policing women’s bodies” after they banned Williams’ “catsuit” in tournament play.

In her op-ed, she praises Williams for speaking up.

“I understand what motivated Williams to do what she did,” she wrote. “And I hope every single girl and woman watching yesterday’s match realizes they should always stand up for themselves and for what they believe is right. Nothing will ever change if they don’t.

Williams “was right to speak her mind, to put a voice to the injustice, and she was right to know when to call for the controversy to end,” she added.

King’s op-ed echoed her tweets from Saturday, which came after a handful of news stories framed Williams as an angry and overly emotional woman.

The Telegraph’s headline said Williams “unleashed furious rant at umpire.” Other articles included mentions of a “meltdown,” an “angry Williams,” a “sore loser,” and an “extraordinary rant.”

“When a woman is emotional, she’s ‘hysterical’ and she’s penalized for it,” King tweeted after the match. “When a man does the same, he’s ‘outspoken’ & there are no repercussions.”

(1/2) Several things went very wrong during the @usopen Women’s Finals today. Coaching on every point should be allowed in tennis. It isn’t, and as a result, a player was penalized for the actions of her coach. This should not happen.

(2/2) When a woman is emotional, she’s “hysterical” and she’s penalized for it. When a man does the same, he’s “outspoken” & and there are no repercussions. Thank you, @serenawilliams, for calling out this double standard. More voices are needed to do the same.